Pipe culvert traverses the Meihe Expressway at an angle of approximately 30 degrees. The geological characteristics encompassed the entire pipe culvert are respectively strongly weathered rock, fully weathered rock, and sub-clay, with hardness ranging from N = 84 to N = 8. The covering soil depth is 4.5 meters. Due to the large variation in hardness and risk for collapse of the roadbed. Therefore, this equipment must meet the following requirements: (1) Have sufficient cutting torque and reliability to adapt to geological conditions of different hardness; (2) Have a large enough cutting area to maintain the stability of the excavation face; reduce the main jacking force to avoid damage to the culvert and ground deformation due to excessive jacking force. (3) Use grouting for friction reduction to prevent soil being carried on the back to ensure the quality of the formed hole. Through repeated comparisons and demonstrations in various aspects such as the development of various schemes, usage costs, impacts on the surrounding environment, and versatility, we have determined to adopt the scheme of multi-cutterhead profiling combined earth pressure balance pipe-jacking. The reasons are as follows:
1.The project has strict environmental protection requirements. The earth pressure balance pipe-jacking machine avoids generating a large amount of slurry that affects the surrounding environment.
2.Compared with competitor’s design (one large and four small cutterheads) , its biggest drawback is the small cutting area (with a cutting ratio of only 86%), large dead zone, and large requirement for jacking force, which is riksy to cause pavement heaving and cracking. Its performance in use is relatively worse than that of the multi-cutterhead profiling .

Our multi-cutterhead profiling has less end reducers, thereby reducing the manufacturing cost. Similarly, the maintenance cost required during use is also greatly reduced. The cutting area of the multi-cutterhead profiling can reach 98%. Both the cutterhead and the profiling cutter frame can rotate forward and backward. The structure is compact, the operation is simple, the maintenance is convenient, and the weight is relatively light, which conforms to the development trend of rectangular section tunneling machines. In addition, due to its very simple structure, it is convenient to be combined into pipe-jacking machines of various specifications in the future to meet the needs of different cutting sections, and has a high reuse rate. For the owner: it can achieve the greatest benefits with the smallest investment.